1. Field of the Invention
The present invention relates to antennas and more particularly to flat panel microwave antennas.
2. Background Information
Satellite antennas of the prior art are easily recognized by their parabolic design. These large and unsightly items can be found throughout the world for communication purposes. The parabolic type shapes range anywhere from 5 to 20 feet in diameter requiring industrial mounts to prevent damage during wind storms due to poor aerodynamic qualities. The conventional satellite dish is typically constructed of metal which is expensive to manufacture and costly to ship.
The purpose of the parabolic type geometry is to ensure reflection and collection of signals at a particular point in space a distance from the inner surface of the antenna used for processing. The common inclination was to use large satellite dishes in order to collect a larger sampling of microwave signals for subsequent processing. For these reasons the common practice has been to manufacture as large of antenna dish as possible using such technology as collapsible dishes and mesh steel dishes for purposes of lowering manufacturing and/or shipping costs.
Many present day satellite communication networks now rely upon a signal beam of highly directive length wherein a refractive type structure is preferable to the aforementioned parabolic reflector type structure. Reflective microwave structures serve to focus the microwave onto a collector set a predetermined distance from the surface of the refractive structure. One such surface refractive antenna lens is disclosed in U.S. Pat. No. 2,547,416 to Skellett which discloses a series of adjacent dielectric rings each having a surface contour of various thickness so as to produce a series of phase delays at a prescribed frequency to produce an emergent wave front. This dielectric antenna presents a complex manufacturing problem having angles that are too sharp and requirements that each ring be machined from a given thickness of material thereby making the cost of manufacturing expensive in term of complexity and weight for the supporting structure.
Another refractive antenna is disclosed in U.S. Pat. No. 4,804,970 issued to Todd which sets forth a multiple wave length conversion arrangement employing dielectric lens in combination with the wavelength selective filter. This enables the antenna to be used as a part of a compact microwave transceiver unit operating on various frequencies. Todd sets forth a convex center piece with a sawtooth type adjacent rings having incline termination edges as they radiate out from the center section of the antenna using squared off ridges.
Another microwave reflector assembly is disclosed in U.S. Pat. No. 4,825,223 issued to Moore. Moore discloses a light weight reflected assembly constructed from a sequence of reflective surfaces using a convex center with a plurality of radiant reflective arrays creating a focal point having gain which is proportional to the radial of the diameter of the parabola divided by the wavelength of the frequency being received. The Moore patent does not disclose radiating reflectors of decreasing height, size, or use of a top member. The reflectors of decreasing height relies upon multiple focal points that require the device to be moved in order to focus to each focal point.
U.S. Pat. No. 4,513,293 issued to Stephens sets forth a frequency selective antenna that teaches away from the use of declining ridges by disclosing the use of all ridges conforming to the same horizontal plane.
Flat plate collectors in the prior art lose energy as the source moves relative to the collector. The antenna with tis reflective mirrors must move in the direction of the source of the transmissions, such as a satellite, in order to receive a strong signal. This movement offsets the remaining frequencies thereby requiring the mirror to be repositioned for each additional frequency selected. This movement offsets the remaining frequencies thereby requiring the mirror to be repositioned for each additional frequency selected. Thus, what is needed in the art is a flat plate array type antenna capable of recording level power signals despite the variance in frequency and an antenna that will adjust to a satellite transmission by simply tilting of the antenna.